Goodness.... I've worked for 2 families long-term.
Family 1 was very inconsiderate- they wouldn't even text me if I was walking into their house with 3 kids vomiting nonstop (I learned quickly to always have multiple changes of clothes in my car). They were also unrealistic in their expectations of sick care such as expecting me to take their very sick child to doctor appointments (which I couldn't do since I don't have any legal rights to be agreeing to medical care). This led to me developing a sick care policy: I don't do fevers over 103°, constant (i mean multiple times am hour) vomiting or diarrhea, and I don't take children to doctor appointments (again its a legal issue).
Family 2 I have my sick care policy included in my contact but it's essentially unneeded. If the kids are sick one of the parents stay home unless it's something minor such as a cold. That's strictly by the parents choice and I very much appreciate it.